How to Store Methyl Methacrylate and Precautions to Neutralize the Effects of the Substance Release - Case Study Example

Technical Aspects Methyl Methacrylate (MMA) is Methyl ester of methacrylic acid (methyl-2-methyl-2-propenoate). Chemical Formula of Methyl Methacrylate is CH2:C(CH3)COOCH3 with the empirical formula C5H8O2. Its CAS No. is 80-62-6 and molecular weight is 100.12. Methyl Methacrylate is a colourless, acrid fruity odour volatile liquid with relatively high vapour pressure (4 kPa at 20°C. It has a moderate water solubility (15.8 g/litre) and low log octanol/water partition coefficient (Kow = 1.38). MMA is a highly flammable liquid and may react violently with polymerisation initiators or curing agents. MMA is corrosive. Commercially available MMA is 99.9% pure. Generally, it contains 0.003% methacrylic acid and 0.03% water. Thermal decomposition products of MMA are oxides of carbon and are very hazardous. Applications MMA is mainly used in plastic industry in the production of cast acrylic sheet, acrylic emulsions, and moulding and extrusion resins. Polymers and copolymers of MMA are also used in waterborne, solvent, and undissolved surface coatings, adhesives, sealants, leather and paper coatings, inks, floor polishes, textile finishes. It is also used in preparation of dental prostheses, surgical bone cements, and leaded acrylic radiation shields, synthetic fingernails and shoe inserts. Exposure The introduction of MMA into the environment is during its transport, bulk storage, and use. This introduction of MMA into the environment contaminates air, soil, and water. Unchecked industrial discharges and spills are also considered some of the reasons for contamination of environment. Depending upon production and releases of MMA, the concentration in the environment will vary. The indirect exposures in the general environment and during use of consumer products as well as exposure in various occupational settings all have ill effects. Exposure to MMA in the workplace could be substantially greater than that in the general environment. Medical and dental professionals, chemical process operators, surgeons and surgical assistants, operating room nurses, dental technicians and hygienists; and beauty technicians (applying synthetic fingernails) face occupational hazards. People who are working inside confined spaces like reactors, boilers, small rooms work and; have exposure to physical and mechanical processes such as heating, pouring, spraying, spills, evaporation are at high risk of exposure to MMA. Legal airborne permissible exposure limits at work places recommended by OSHA (Occupational Safety and Health Administration), NIOSH (national Institute of Occupational Safety and Health) and ACGIH (American Conference of Governmental Industrial Hygienists are as follows: OSHA and NIOSH TWA (10 hours): 100 ppm (410 mg/m3), ACGIH TWA (sensitizer): 50 ppm, ACGIH STEL (sensitizer): 100 ppm. Health Hazards MMA is on the special health hazard substance list because it is flammable and reactive. On NFPA scale (0 to 4), MMA is rated for Health =2, for Fire=3 and for Reactivity=2. Risk Phrases codes for MMA are as follows: Highly flammable:R11, Irritating to respiratory system: R37, Irritating to skin: R38, May cause sensitization by skin contact: R43. EC Safety phrases Under EC legislation (UK), Safety phrase codes for MMA are as follows: Avoid contact with skin: S24, Wear suitable gloves: S37, If swallowed, seek medical advice immediately and show this container or label: S46. Human hazards Typical exposure limits of MMA are in the range 25 to 50 ppm. Acute health effects on short term exposure to MMA are seen immediately. MMA is lachrymator and; strong irritant to nose, throat and skin. This chemical can cause allergic reactions, rash etc. when it comes in contact with the skin. MMA can cause respiratory problems like coughing, shortness of breath, pulmonary edema etc. Exposure to high concentrations of MMA can cause dizziness, irritability, difficulty with concentration and reduced memory. Chronic or long term health effects include reproductive disorders, cancer, nervous system disorders, skin allergic reactions on minimum exposure to MMA, etc. In addition to this, MMA may cause liver and kidney disorders. Detailed medical evaluation should be carried out at the onset of above mentioned clinical symptoms. Medical tests may include chest X-ray, examination of nervous system, liver function test, kidney function test, skin tests for allergic reactions etc. Ecological hazards MMA is found to be toxic to fish, invertebrates and algae. Acute toxic effects can be severe on short term exposure to MMA and might lead to death in animals, fish, birds etc. It also suppresses the growth of the plants. The ecotoxicity data is as follows: Fish Toxicity: 191000 ug/L 96 hour(s) LC50 (Mortality) Bluegill (Lepomis macrochirus) Invertebrate Toxicity: 1042 mg/L 24 hour(s) EC100 (Abundance) Water flea (Daphnia magna) Algal Toxicity: 37000 ug/L NR year(s) (Population Growth) Green algae (Scenedesmus quadricauda) Chronic ecological effects may comprise of shortened life span, lower fertility, and changes in behaviour in animals, aquatic life etc Operation, Storage and Transport In 1993, International Programme on Chemical Safety (IPCS) prepared The International Chemical Safety Card for methyl methacrylate (ICSC 0300). MMA should be stored, handled and transported in accordance with all current regulations and standards. The work related to MMA should be carried out after proper training of handling procedures and storage conditions. The hazard and warning information should be posted at MMA working places. All the information regarding health and safety should be given to operators through ongoing education and training. MMA should be used, handled, manufactured or stored at locations where explosion proof electrical equipment and fittings are available. MMA should be stored in tightly closed containers at low temperature in a well ventilated area, away from moisture, heat, ultraviolet and ionizing radiations. MMA is prone to autopolymerisation, especially in light. Therefore, for storage and transportation additives like 2-100 ppm methyl ether of hydroquinone and 25-100 ppm hydroquinone are added which acts as inhibitors. Other phenolic inhibitors, such as dimethyl tert-butylphenol, can also be used as substitutes. If the concentration of inhibitors in MMA is small, even without application of heat, explosion may take place. This is especially true in case of emergency situations like leakage or spill. Since MMA is incompatible with strong oxidizing agents, peroxides, bases, acids, reducing agents, amines, halogens, nitric acid, nitrates, polymerization catalysts. The contact with these substances can cause severe explosive reactions. Therefore MMA should be kept away from these incompatible substances. Physical damage of MMA should be prevented. It should be warehoused in a separate location. MMA should be stored with flammable liquids. Since MMA react by itself, closed containers may rupture violently or explode, if exposed to heat. Therefore heat, flames, sparks and other sources of ignition should be avoided. It should not be stored under inert atmosphere and should be used within six months. The containers containing MMA should be opened and closed with non-sparking tools and equipments only. The transfer of MMA should be carried out in grounded and bonded metal containers. Transport For the MMA transport while shipping, the labeling requirements, packaging conditions should be followed in accordance with the specified regulations. U.S. DOT 49 CFR 172.101: Proper shipping name: Methyl methacrylate monomer, stabilized ID Number: UN1247 Hazard Class Or Division: 3 Packing Group: II Labeling Requirements: 3 Canadian Transportation Of Dangerous Goods: Shipping Name: Methyl methacrylate monomer, stabilized UN Number: UN1247 Class: 3 Packing Group/Risk Group: II Protective Measures Personal protective measures Inculcating good working practices can help to reduce the risk on hazardous exposure. People who are exposed to MMA should wear splash resistant safety goggles, impervious gloves and appropriate chemical resistant clothing. ACGIH advises use of polyvinyl alcohol as protective material. An approved respirator equipped with an organic vapour cartridge, emergency eye wash fountain should be installed in the area. The working area should have exhaust to control the MMA exposure limits. The operators should wash their hands thoroughly before eating, drinking, smoking, or using the toilet. First Aid Measures Before calling the doctor following first aid measures should be taken on a person who is at high risk due to MMA exposure. Inhalation: The patient suffering from adverse effects due to inhalation should be taken away from the place immediately. Artificial respiration if needed should be given instantly. Skin contact: The irritated skin should be washed skin with soap and water for at least 15 minutes. Remove contaminated clothing and shoes and decontaminate them before reuse. Eye contact: The eyes should be flushed with plenty of water for at least 15 minutes. . Ingestion: If vomiting occurs, keep head lower than hips to help prevent aspiration. If person is unconscious, turn head to side. Gastric lavage and activated charcoal slurry should be given to a patient by physician. Fire Fighting Measures Fire and Explosion Hazards: MMA comes under Flammability Class (OSHA): IB. Since MMA react by itself, closed containers may rupture violently or explode, if exposed to heat. Vapor/air mixtures are explosive above flash point 50 F. The fire is extinguished using extinguishing media like alcohol resistant foam, carbon dioxide, regular dry chemical or water. Accidental Release Measures On accidental release of MMA into the environment i.e. air, water, soil the following steps should be taken immediately. To clean up spills the recommendations given by OSHA 1910.120(q) should be followed by employees. Air Release: Water is sprayed to make vapour soluble in water. Stay upwind and in elevated areas. Soil Release: The contaminant should be mixed with sand or other non-combustible material and kept in dike for later disposal. Water Release: Unwanted MMA mixed with water should be absorbed with absorbent sheets, activated carbon, spill-control pads or pillows. Also, trapped material is removed with suction hoses and then kept at proper place for disposal. Other measures: Sources of ignition like heat, flames, sparks should be taken away from MMA release area. The hazard area should be immediately isolated to keep unnecessary people away. Local Emergency Planning Committee and State Emergency Response Commission should be informed immediately for release greater than or equal to RQ (U.S. SARA Section 304). Disposal of MMA The disposal of MMA should be carried out according to U.S. EPA 40 CFR 262. Hazardous Waste Number(s): U162. Read More